A light emitting diode (LED) is a two-lead semiconductor light source. More simply, LEDs are essentially p-n junction diodes that emit light when activated. This effect is called electroluminescence, and the color of the light emitted is determined by the energy band gap of the semiconductor material. Traditional LEDs are typically of a size on the order of hundreds of microns. In contrast, micro-sized LEDs or micro LEDs are of a size on the order of tens of microns or less. Micro LED displays can provide brighter screens and wider color gamuts than that achievable using traditional LED or organic LED (OLED) displays.
Micro LEDs are an emerging technology area, and demand for micro LED-based technology platforms in devices such as consumer wearables (for example, watches, augmented reality devices, virtual reality devices) and mobile or stationary display devices is increasing rapidly. Such devices may require a full color range, high brightness (for example, more than 2,000 cd/m2), high contrast, low power requirements, high pixel densities (for example, more than 2,500 pixels per inch), and low manufacturing costs.
To make active matrix micro LED display panels capable of satisfying these requirements, many workflows produce individual micro LEDs that are tuned to emit red, green or blue colors on separate wafers. These micro LEDs are then transferred from the original wafers to thin film transistor (TFT) backplanes to make red, green, and blue (RGB) pixels that make up the active matrix LED display panel. In other words, conventional micro LEDs may be made up of micron sized digital components formed on appropriate substrates, separated from those substrates, and then placed together on one new substrate.